On Fri, Jun 28, 2013 at 8:48 AM, Matt Rhys-Roberts <
matt.rhys-roberts@envinsci.co.uk> wrote:

> In the world of 4-20mA instrumentation, is there any such thing as a
> typical or ideal input resistor at the receiver end?
>
> I notice a few diagrams using a 250R res across the Rx input terminals,
> which seems a default value. To some extent I guess it can be altered to
> provide the required voltage from the current range.
>
> It seems that I need to specify enough voltage at the Tx end, to
> overcome both the cable's length and the Rx's Zin. Both these
> resistances are a little undefined to me at this point.
>
> Any personal experiences about this please?
>

All the 4-20mA instrumentation sensors we design use 49R9 as the sense
resistor.

Bill

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